Optical display system and method for creating a theatrical illusion

ABSTRACT

An optical display system and method comprises provision of two angularly disposed side mirror surfaces, a bottom mirror surface angularly disposed with respect to the side mirror surfaces, and a projection sceeen angularly disposed with reference to such mirror surfaces. An image projected on the screen provides an object which because of the mirror arrangement creates a plurality of virtual images.

United States Patent 1191 Worland Dec. 4, 1973 OPTICAL DISPLAY SYSTEMAND METHOD FOR CREATING A THEATRICAL ILLUSION [75] Inventor: DonovanWorland, San Francisco,

Calif.

[73] Assignee: Walter Landor Associates, San

Francisco, Calif.

[22] Filed: May 24, 1972 [21] Appl. No.: 256,428

51 Int. Cl. G03b 37/00 [58] Field of Search 352/69, 85, 86, 89, 352/244;272 1, 2, 3, s R, s M,9, 10, 11,13;

[56] References Cited UNITED STATES PATENTS 3/1970 Markson 352/85 X4/1942 Waller et a]. 52/6 X H1903 Diem 272/8 M Primary Examiner-7Att0rneyStanley Bialos [5 7] ABSTRACT An optical display system andmethod comprises provision of two angularly disposed side mirrorsurfaces, a bottom mirror surface angularly disposed with respect to theside mirror surfaces, and a projection sceeen angularly disposed withreference to such mirror surfaces. An image projected on the screenprovides an object which because of the mirror arrangement creates aplurality of virtual images.

11 Claims, 7 Drawing Figures 1% L001? 39 :MJRROR');

FTi I 1 PATENTED 75 SHEEI 1 0F 4 PAIENTED 4 I973 sum 3 or 4 WALL MIRRORSCREEN SUMMARY AND OBJECTS Summarizing the invention hereof, a system ofmirrors is provided comprising two side mirror surfaces angularlydisposed withrespect to each other, and a bottom mirror surfacebetween-the side mirror surfaces. As a result, when an object adjacentthe mirrors is viewed by an observer, a plurality of virtual images isseen by the observer. Such object is formed on a projection screenangularly disposed with reference to the mirror surfaces by projectionfrom a projector.

To create a theatrical illusionary effect, the side mirror surfaces aredesirably at a 90 angle with respect to each other and with respect tothe bottom mirror surface with the front edges of the side mirrorsurfaces curved in the arc of a great circle from adjacent the top ofthe apex of the side mirror surfaces to the bottom of such surfaces;andthe projection screen is desirably of triangular shape, having thesurface shape of a spherical triangle to form with-the mirror surfacesan enclosure in the form of a dome of substantially one-eighth of asphere. As a result, a viewer within the dome has the sensation of beingwithin a hollow sphere with images present above, below and about suchviewer.

A viewing area for spectators is provided adjacent the apex between theside wall surfaces; and only a single projector is required forprojecting an image onto the screen which is a conventional projectionscreen. Advantageously, the projector is located adjacent the apex ofthe quarter dome sufficiently high to project the image above thespectators. To obviate distortion, the projecting system includes a wideangle lens having a substantially spherical surface; and a maskingmember having a substantially triangular aperture is associated with thelens to conform the image to the triangular screen. The projectingsystem is preferably such that the projection fills substantially theentire screen.

The image projected onto the screen is the object or objects reflectedby the mirrors which provide or form the plurality of virtual images.The term image on the screen is employed'to include a plurality ofimages which may be still images or a moving picture. In any event, itis the image on the screen which forms the object reflected by themirrors to provide the plurality of virtual images.

to a spectator of being within a hollow sphere and seeing images above,below, and around him, and which is yet of simple construction notrequiring a complex mirror or projection system. Other objects of theinvention will become apparent from the following more detaileddescription and accompanying drawings in which:

DESCRIPTION OF DRAWINGS FIG. 1 is a schematic isometric, elevationalview, for purposes of explanation, illustrating the formation of virtualimages of an object with two side mirror surfaces at a right angle withrespect to each other;

FIG. 2 is a schematic plan view of FIG. 1 to illustrate further thelocation of virtual images which are present;

FIG. 3 is a schematic perspective view, illustrating additional virtualimages produced below the plane of a bottom mirror surface positioned ata right angle with respect to the 90 angularly related side mirrorsurfaces shown in FIG. 1; reflections of the side mirrors being omittedfor purposes of clarity;

FIG. 4 is a schematic horizontal section of the theatre dome hereof,taken in planes indicated by line 44 in FIG. 5;

FIG. 5 is a schematic vertical section taken in a plane indicated byline 5-5 in FIG. 4;

FIG. 6 is a fragmentary schematic sectional elevation looking at anangle indicated by the direction arrow 6 in FIG. 4; and

FIG. 7 is an exploded view illustrating a projection lens and thetriangularly apertured masking member cooperating with such lens.

DETAILED DESCRIPTION Referring to FIG. 1 for purposes of explanation ofthe instant invention, two side mirror reflecting surfaces 2 and 3 aredepicted at an angle of 90 relative to each other; and reflections ofthese mirrors are indicated at 2 and 3', respectively. It will be notedthat an object 4, illustrated schematically as a sphere, positionedbetween the side mirrors will result in the formation of three virtualimages, namely side images 6 and 7, and central image 8, the positionsof which will depend upon the position of the viewer and that of theobject relative to the mirrors. Each of these virtual images will be thesame size as the object and will appear behind the mirrors as iswell-known in optics. The solid lines 9 indicate the distances betweenobject 4 and the front of the respective mirrors while the broken lines10 behind the mirrors indicate the equal distances of the virtual images6 and 7 behind the mirrors. Solid lines 11 indicate a schematicreflecting ray which results in central virtual image 8 while brokenline 12 indicates extension of such ray to central virtual image 8.Crosses 13 indicate the actual planes of the mirrors. FIG. 2 illustratesthe position of object 4 and the virtual images 6, 7, and 8 in planelevation.

Thus, with the two mirrors at a 90 angle with respect to each other asshown, there are always present four images which can be found by theviewer, namely the object or real image 4 and the three virtual images6, 7 and 8. All of these four images will appear to lie in a circlehaving its center at the apex of the angle or point intersection of themirrors. This phenomenon is not limited to mirrors placed at an angle of90 with reference to each other because if the mirrors are at an angleof, for example, five virtual images can be seen in addition to theobject, making six images in all; and at a 45 angle seven virtual imagesin addition to the object image will be present. The angle is most 1desirable for the effect to be obtained by the invention tual imagebottom mirror 17 behind the apex, and virtual image bottom mirrors 18and 19 behind side mirrors 2 and 3, respectively. There are tworeflections of the side mirrors above the plane of bottom mirror 16 andfour below, but these are omitted for clarity.

A virtual image 4 of object 4 will thus appear below bottom mirror 16,the same distance as object 4 is above such mirror. Likewise, virtualimages 6', 7, and 8' of the virtual images 6, 7 and 8, respectively,will appear below the respective virtual image mirrors 18, 19 and 17,respectively, thus providing in all a total of eight images, namely thereal object image 4, and seven virtual images 4, 6, 7, 8, 6, 7' and 8.Four of these images, including the object image 4, will be present in aplane above bottom mirror 16 and four of them in a plane below thebottom mirror; and they will lie on the surface of a sphere, the centerof the sphere being at the apex junction of the three mirrors.

In the invention hereof, a floor or bottom mirror, between side mirrorsprovides the desired additional virtual images below the bottom mirrorwhich are present and which can be observed by a viewer, to produce anunusual illusionary effect when the mirrors are employed in cooperationwith a projection screen between the side mirrors. Although illusionaryeffects can be obtained by having the mirrors angularly disposed at anangle other than 90, for the desired theatrical effect hereof, it ismost advantageous to have the mirrors disposed at a 90 angle relative toeach other with a projection screen of one-eighth spherical surfacebetween the side mirrors because a viewer within a one-eighth sphereenclosure formed of such mirrors and screen has the sensation of beingwithin a hollow sphere forming a substantially spherical projectionscreen and thus seeing images above, below and all around him. In thisconnection, the foregoing description of FIGS. 1 through 3 refers to asingle object as the image for purposes of clarity, but it should benoted that a plurality of objects will produce a multiple effect; andwhen the object viewed in a motion picture projected onto the projectionscreen, startling effects are produced as will be vdescribed withreference to the theatrical embodiment of the invention illustrated inFIGS. 4 through 7.

The theatre comprises a building structure having side walls 31 at anangle of 90 with respect to each other and which have curved front edges32 which are 90 arcs of a great circle. These edges curve downwardlyfrom the top of the apex of the angle which the walls make, to theirbottom edges. Adjacent the apex is a curved spectator viewing platform33 which may be provided with seats if desired; and at the rear, one ofwalls 31 is provided with an entrance 34 which may be closed by door 36.The curved front edges 32 of side walls 31 are connected to a front wall37 which has the shape of a spherical triangle with its apex betweenside walls 31 at the top where they meet, and its base at the front ofthe bottom.

The inside surfaces of side walls 31 are provided with smooth mirrorreflecting finishes or with mirrors if so desired, indicated at 38,which cover substantially the entire visible areas of the side walls,and the floor 39 or bottom of the structure is also covered with asmooth mirror or reflecting surface 41. Also the inside surface of frontwall 37 is provided with a conventional projection screen surface 42which is adapted to receive an image, either a still image from aprojection slide or a motion picture image, which provides the objectfrom which the multitude of virtual images are produced in the mannerdescribed with reference to FIG. 3.

The described enclosure structure is in the form of a dome which isone-eighth of a sphere. As a result, a viewer wihtin the dome onplatform 33 has the illusion of being inside a complete optical spherewhich forms a projection screen which is substantially a complete hollowsphere, with images above, below and all around the viewer. Such viewermay not see the entire area of the spherical screen at one time but thescreen and the images thereon are always present and by looking aroundall the images can be seen by the viewer.

In the case of a motion picture projection, startling effects areproduced. For example, if the projection on the spherical surface,triangular screen depicts a flight of birds, the viewer will observebirds all around him which actually makes him feel as if he is a part ofthe presentation. Astounding astronomical and other effects can beproduced by projections on the screen.

The projection means may be at any suitable point, but it is preferredto position it at the apex of the side mirror surfaces, sufficientlyhigh to clear the heads of the spectators. Such projection systemincludes a projector (not shown) in association with a wide angle lens51 having a substantially spherical surface 52 to cooperate with thespherical surface of the projection screen surface 42. A well-known,so-called Fish eye type lens having an angle of at least sphericalcoverage is preferred to obviate distortion, and in this connection,such type of lens has sufficient depth of focus to accommodate thecurved projection screen.

Projection screen 42 could be a trangular, flat projection surface.However, if a flat screen is used, then the viewer obtains the illusionof being within a prism rather than within a sphere; and for this reasonthe spherical surface screen is most desirable. Although it is notnecessary to fill the entire screen with the projected image, this isdesirable for best effects as is illustrated diagramatically by brokenlines 54 in FIG. 6; and because the projection screen is essentiallytriangular, a masking plate is provided in association with the lens, asshown in FIG. 7, which has an approximately triangular aperture 56 toconform the image to the triangular projection screen.

The one-eighth sphere construction is advantageous because it providesthe desired optical illusion with minimum distortion and confusion tothe viewer. However, domes of lesser sphere segments may be employed,such as a one-sixteenth sphere, but then the increased number of imagesmay cause excessive confusion to the viewer with accompanyingdistortion. Spherical sections of greater size than one-eighth willproduce a lesser number of virtual images.

Any suitable size may be employed for the theatre, a suitable size beinga dome of one-eighth of a sphere of about 50 foot radius with viewingplatform 33 as far back of projection screen 42 as convenient so as tohave the floor mirror surface in front of the screen of a relativelylarge area. As illustrated in FIG. 4, the platform is conveniently aboutone-third away from the apex of the wall mirrors. In such embodiment theprojector is preferably located about twelve feet above the floor.mirror surface.

I claim:

1. An optical display system creating the effect to a viewer of beingabove within a substantially complete hollow sphere with images allaround him comprising a floor having a circularly curved front edge andopposite substantially straight side edges meeting substantially at anangle to form an apex rearwardly of said curved front edge, a viewingstation between said curved front edge and said apex, a projectionscreen having the shape of a spherical triangle extending upwardly fromsaid curved front edge of the floor and over said viewing station andhaving circularly curved side edges which substantially meet at an apexaove said floor apex, a pair of side wall reflecting surfaces extendingfrom such apices and having substantially circularly curved front edgessubstantially meeting the curved side edges of said screen, each of saidsubstantially circularly curved front edges having a radius of curvaturesubstantially equal to the length of said side edges, the curvature ofsaid projection screen conforming substantially to the curvature of saidfront edges, a reflecting surface on said floor between said side wallreflecting surfaces and extending rearwardly from said screen, and meansfor projecting an image on said screen.

2. The optical display system of claim 1 wherein a projecting systemincluding a wide angle lens is provided to project an image onto saidprojection screen, and a masking member having a substantiallytriangular aperture is cooperable with said lens to conform th image tothe screen.

3. The optical display system of claim 2 wherein the projected image isa still image.

4. The optical display system of claim 2 wherein the projected image isa motion picture.

5. The optical display system of claim 1 wherein each of said curvededges defines an arc of substantially 90 to provide an enclosed domewhich is one-eighth of a sphere.

6. An optically created hollow projection screen comprising two sidereflecting surfaces each having curved front edges substantially 90 ofan arc of a circle and two straight edges forming substantially a rightangle, said two surfaces being angularly disposed with re-.

triangle with curved edges substantially meeting the curved edges ofsaid floor and side reflecting surfaces.

7. The optically created hollow projection screen of claim 15 whereinthe screen is a one-eighth spherical triangular surface, and forms aone-eighth spherical dome with said reflecting surfaces.

8. A theatre having an optical display system for creating the effect toa viewer within the theatre of being within a hollow sphere andobserving a plurality of images which are present above, below, andabout such viewer, comprising a dome which is substantially oneeighth ofa sphere, having side wall mirror surfaces disposed at a substantiallyangle with respect to each other, a bottom floor mirror surface disposedat a substantially 90 angle with respect to said side wall mirrorsurfaces, and a single projection screen having the surface shape of aspherical triangle angularly disposed with respect to said side wall andbottom floor mirror surfaces; an area adjacent the apex between saidside wall surfaces for spectators; and means for projecting an imageonto said screen including a wide angle lens having a substantiallyspherical surface, and a masking member cooperable with said lens havinga substantially triangular aperture to conform the image to said screen.

9. The theatre of claim 8 wherein said mirror surfaces are planarsmooth.

10. The method of creating an optical illusion to a viewer of observinga plurality of images of an object which comprises projecting an imageon a projection screen which is l/8 of a sphere to form such object,providing a pair of side mirror surfaces disposed at substantially aright angle to each other leading from front curved edges of said screento form a plurality of virtual images of said object, and providing abottom mirror surface meeting the bottom curved edge of said screen andangularly disposed at'substantially right angles with respect to saidside mirror surfaces to form additional virtual images of said firstmentioned virtual images.

11. The method of claim 10 wherein the mirror sur faces and screen forman enclosed dome which is substantially one-eighth of a sphere to createthe illusion of a viewer within the dome being within a hollow sphere.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,776,621 Dated December 4, 1973 Inventorfii) Donovan wot-land It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 3, line 40, "in" should read --is-; Column 4, line 66 (Claim 1,line 2 of the Claim), "above" should read --entirely--; Column 6, line 4(Claim 7, line 2 of the Claim), numeral "15" should read --6-.

Signed and sealed this 16th day of April 19m.

(SEAL) Attest't I EDWARD M.F.LETCHER c. MARSHALL DAM Attesting OfficerCommissioner of Patents UNITED STATES PATENT OFFICE CE'HFICATE lCORRECTION Dated December t, 1973 Patent No.

Donovan worland InventorQG) identified patent It is certified that errorappears in the aboveand that said Letters Patent are hereby corrected asshown below:

line +0, "in" should read --is--, Column 4,

2 of the Claim), "above" should read line 2 of the. Claim),

Column 3,

(Claim 7,

line 66 (Claim 1, line --entirely--; Column 6, ling 4 numeral "15"should read Signed and sealed this 16th day of April 197M.

(SEAL) Attest v EDWARD M.F.LETCHER c. MARSHALL DAM Attesting OfficerCommissioner of Patents FQBM oqoso (10-69)

1. An optical display system creating the effect to a viewer of beingabove within a substantially complete hollow sphere with images allaround him comprising a floor having a circularly curved front edge andopposite substantially straight side edges meeting substantially at anangle to form an apex rearwardly of said curved front edge, a viewingstation between said curved front edge and said apex, a projectionscreen having the shape of a spherical triangle extending upwardly fromsaid curved front edge of the floor and over said viewing station andhaving circularly curved side edges which substantially meet at an apexaove said floor apex, a pair of side wall reflecting surfaces extendingfrom such apices and having substantially circularly curved front edgessubstantially meeting the curved side edges of said screen, each of saidsubstantially circularly curved front edges having a radius of curvaturesubstantially equal to the length of said side edges, the curvature ofsaid projection screen conforming substantially to the curvature of saidfront edges, a reflecting surface on said floor between said Side wallreflecting surfaces and extending rearwardly from said screen, and meansfor projecting an image on said screen.
 2. The optical display system ofclaim 1 wherein a projecting system including a wide angle lens isprovided to project an image onto said projection screen, and a maskingmember having a substantially triangular aperture is cooperable withsaid lens to conform the image to the screen.
 3. The optical displaysystem of claim 2 wherein the projected image is a still image.
 4. Theoptical display system of claim 2 wherein the projected image is amotion picture.
 5. The optical display system of claim 1 wherein each ofsaid curved edges defines an arc of substantially 90* to provide anenclosed dome which is one-eighth of a sphere.
 6. An optically createdhollow projection screen comprising two side reflecting surfaces eachhaving curved front edges substantially 90* of an arc of a circle andtwo straight edges forming substantially a right angle, said twosurfaces being angularly disposed with respect to each other with theirstraight edges substantially meeting, a floor reflecting surface betweensaid side reflecting surfaces and having a curved front edge which issubstantially 90* of the arc of a circle, and a single projection screenhaving the shape of a spherical triangle with curved edges substantiallymeeting the curved edges of said floor and side reflecting surfaces. 7.The optically created hollow projection screen of claim 15 wherein thescreen is a one-eighth spherical triangular surface, and forms aone-eighth spherical dome with said reflecting surfaces.
 8. A theatrehaving an optical display system for creating the effect to a viewerwithin the theatre of being within a hollow sphere and observing aplurality of images which are present above, below, and about suchviewer, comprising a dome which is substantially one-eighth of a sphere,having side wall mirror surfaces disposed at a substantially 90* anglewith respect to each other, a bottom floor mirror surface disposed at asubstantially 90* angle with respect to said side wall mirror surfaces,and a single projection screen having the surface shape of a sphericaltriangle angularly disposed with respect to said side wall and bottomfloor mirror surfaces; an area adjacent the apex between said side wallsurfaces for spectators; and means for projecting an image onto saidscreen including a wide angle lens having a substantially sphericalsurface, and a masking member cooperable with said lens having asubstantially triangular aperture to conform the image to said screen.9. The theatre of claim 8 wherein said mirror surfaces are planarsmooth.
 10. The method of creating an optical illusion to a viewer ofobserving a plurality of images of an object which comprises projectingan image on a projection screen which is 1/8 of a sphere to form suchobject, providing a pair of side mirror surfaces disposed atsubstantially a right angle to each other leading from front curvededges of said screen to form a plurality of virtual images of saidobject, and providing a bottom mirror surface meeting the bottom curvededge of said screen and angularly disposed at substantially right angleswith respect to said side mirror surfaces to form additional virtualimages of said first mentioned virtual images.
 11. The method of claim10 wherein the mirror surfaces and screen form an enclosed dome which issubstantially one-eighth of a sphere to create the illusion of a viewerwithin the dome being within a hollow sphere.